Comparison of the Metabolism and Receptor Binding of Testosterone and 17β-Hydroxy-5α-Androstan-3-One in Normal Skin Fibroblast Cultures: Influence of Origin and Passage Number

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Abstract
Measurements of receptor concentration and enzyme activities in cultured fibroblasts derived from skin biopsies should faithfully reproduce genetically determined donor characteristics. Receptor binding was compared in a series of normal human skin fibroblast lines after incubation with 1 nM [3H]-testosterone or [3H]5.alpha.-dihydrotestosterone [3H]DHT. In most cell lines, higher binding capacities were noted after incubation with DHT than after incubation with testosterone. In some lines, the reverse was observed. Evidence is presented that even after incubation with testosterone, DHT was the major compound bound to the receptor protein. Moreover, a clear-cut correlation could be demonstrated between 5.alpha.-reductase activity and receptor binding estimated from incubations with testosterone. The fact that in some cell lines estimates of binding capacities derived from studies with testosterone consistently exceeded those derived from studies with DHT suggests that intracellularly produced DHT may be processed differently than exogenously added DHT. The influence of passage number on 5.alpha.-reductase activity, 17.beta.-hydroxysteroid dehydrogenase activity and receptor binding has been studied in 3 cell lines [M9, M13 [human foreskin] and M7 [human labia majora]]. Receptor binding remains fairly constant between passages 5-44. 5.alpha.-Reductase activity increased in the 3 cell lines studied, whereas 17.beta.-hydroxysteroid dehydrogenase activity showed unpredictable changes.